A technique in which images of all directions at an imaging spot are imaged to make an omnidirectional view at the imaging spot into one piece of image has been known. For example, in Patent Literature 1, the invention of an observation device that converts images of all directions at an imaging spot into an image for display, and displays the image for display on a display unit of a cylindrical casing is disclosed. Moreover, a technique in which a part of an image in which all directions at an imaging spot are put into one piece of image is displayed on a display of a personal computer in such a form that a predetermined direction is actually viewed from an imaging spot has been known. Furthermore, a technique of changing a display range (direction) of an image arbitrarily according to the operation of a user has been known.
However, with the conventional techniques, it has been difficult for a user to grasp relation between a display range of an image that is currently displayed on a screen and information indicating a list of viewpoints on the image.